Human footprints at White Sands National Park in New Mexico show that human activity occurred in the Americas long as 23,000 years ago – about 10,000 years earlier than previously thought. Footprints found at White Sands National Park in New Mexico provide the earliest unequivocal evidence of human activity in the Americas and provide insight into life over 23,000 years ago. The findings are described in a Science journal article co-authored by University of Arizona archaeologist Vance Holliday. Researchers Jeff Pigati and Kathleen Springer, with the U.S. Geological Survey, used radiocarbon dating of seed layers above and below the footprints to determine their age. The dates range in age and confirm human presence over at least two millennia, with the oldest tracks dating back 23,000 years. This corresponds to the height of the last glacial cycle, during something known as the Last Glacial Maximum, and makes them the oldest known human footprints in the Americas. It was previously thought that humans entered America much later, after the melting of the North American ice sheets, which opened up migration routes. "Our dates on the seeds are tightly clustered and maintain stratigraphic order above and below multiple footprint horizons – this was a remarkable outcome," Springer said. One of the oldest footprints found at the site. The footprints tell an interesting tale of what life was like at this time. Judging by their size, the tracks were left mainly by teenagers and younger children, with the occasional adult. Holliday and study co-author Brendan Fenerty, a UArizona doctoral student in the Department of Geosciences, documented basic geologic layering and dating in trenches on the White Sands Missile Range near the discovery site several years before the tracks were found. Tracks of mammoth, giant ground sloth, dire wolves and birds are also all present at the White Sands site. Tracks of mammoth, giant ground sloth, dire wolves and birds are also all present at the site. The human tracks at White Sands were first discovered by David Bustos, resources manager at the park. The team also pioneered non-invasive geophysical techniques to help locate the site. Tommy Urban, from Cornell University, led this part of the work. "Detection and imaging with nondestructive technology has greatly expanded our capacity to study these remarkable footprints in their broader context," he said. Traditional archaeology relies on the discovery of bones and tools but can often be difficult to interpret. Human footprints provide unequivocal evidence of presence and also of behavior. We respectfully acknowledge the University of Arizona is on the land and territories of Indigenous peoples. Today, Arizona is home to 22 federally recognized tribes, with Tucson being home to the O’odham and the Yaqui. Committed to diversity and inclusion, the University strives to build sustainable relationships with sovereign Native Nations and Indigenous communities through education offerings, partnerships, and community service. © 2024 The Arizona Board of Regents on behalf of The University of Arizona.